Merge pull request #10 from tfrench-uber/testerrors

validate input and output before unmarshal

unmarshal.go

@@ -19,6 +19,10 @@ var jsonNumberType = reflect.TypeOf(json.Number(""))
 
 // Unmarshal used to unmarshal nested json using "njson" tag
 func Unmarshal(data []byte, v interface{}) (err error) {
+	if !gjson.ValidBytes(data) {
+		return fmt.Errorf("invalid json: %v", string(data))
+	}
+
 	// catch code panic and return error message
 	defer func() {
 		if r := recover(); r != nil {
@@ -33,7 +37,11 @@ func Unmarshal(data []byte, v interface{}) (err error) {
 		}
 	}()
 
-	elem := reflect.ValueOf(v).Elem()
+	rv := reflect.ValueOf(v)
+	if rv.Kind() != reflect.Ptr || rv.IsNil() {
+		return fmt.Errorf("can't unmarshal to invalid type %v", reflect.TypeOf(v))
+	}
+	elem := rv.Elem()
 	typeOfT := elem.Type()
 	for i := 0; i < elem.NumField(); i++ {
 		field := elem.Field(i)

unmarshal_test.go

@@ -8,6 +8,77 @@ import (
 	"github.com/google/go-cmp/cmp"
 )
 
+func TestUnmarshalInvalidJson(t *testing.T) {
+	json := `
+	BAD JSON %% @
+	##
+	}`
+
+	type Name struct {
+		First string `njson:"first"`
+		Last  string `njson:"last"`
+	}
+
+	type User struct {
+		Name    Name   `njson:"name"`
+		Age     int    `njson:"age"`
+		Friends []Name `njson:"friends"`
+	}
+
+	actual := User{}
+
+	if err := Unmarshal([]byte(json), &actual); err == nil {
+		t.Error("error should not be nil")
+	}
+}
+
+func TestUnmarshalError(t *testing.T) {
+	json := `
+	{
+        "name": {"first": "Mohamed", "last": "Shapan"},
+        "age": 26,
+        "friends": [
+            {"first": "Asma", "age": 26},
+            {"first": "Ahmed", "age": 25},
+            {"first": "Mahmoud", "age": 30}
+        ]
+	}`
+
+	if err := Unmarshal([]byte(json), nil); err == nil {
+		t.Error("error should not be nil")
+	}
+}
+
+func TestUnmarshalByValueError(t *testing.T) {
+	json := `
+	{
+        "name": {"first": "Mohamed", "last": "Shapan"},
+        "age": 26,
+        "friends": [
+            {"first": "Asma", "age": 26},
+            {"first": "Ahmed", "age": 25},
+            {"first": "Mahmoud", "age": 30}
+        ]
+	}`
+
+	type Name struct {
+		First string `njson:"first"`
+		Last  string `njson:"last"`
+	}
+
+	type User struct {
+		Name    Name   `njson:"name"`
+		Age     int    `njson:"age"`
+		Friends []Name `njson:"friends"`
+	}
+
+	actual := User{}
+
+	if err := Unmarshal([]byte(json), actual); err == nil {
+		t.Error("error should not be nil")
+	}
+}
+
 func TestUnmarshalSmall(t *testing.T) {
 	json := `
 	{